Electrical connector means with automatic thermal responsive overload circuit breaker



May 28, 1968 K. M. DELAFRANGE 3,335,061

ELECTRICAL CONNECTOR MEANS WITH AUTOMATIC THERMAL RESPONSIVE OVERLOADCIRCUIT BREAKER Filed July 5, 1965 IN VEN TOR. leg/M5774 M' WFkflA/m,

United States Patent ELECTRICAL CONNECTOR MEANS WITH AUTO- MATIC THERMALRESPONSIVE OVERLOAD CIR- CUIT BREAKER Kenneth M. Delafrange, 96Washington Ave., Westwood, NJ. 07675 Filed July 5, 1966, Ser. No.562,835 1 Claim. (Cl. 337-1) ABSTRACT OF THE DISCLOSURE An electricalconnector and circuit breaker operable in connecting extension circuitsfrom an outlet in a main circuit and in protecting againstcurrent'overloads in the circuits above a predetermined current carryingrange for which the circuit breaker is designed, the structure embodyingin use a normally closed thermal responsive circuit breaker forautomatically opening the circuit on overload with means preventingarcing and reclosing of the circuit breaker, this means being manuallyoperable to reset the breaker, and, when reset to open the breaker atthe will of a user.

This invention relates to an electrical plug connector with automaticcurrent overload circuit breaker. More particularly, it relates to aplural conductor circuit extension connector with contacts forconductive association with an electrical outlet and having a thermalresponsive overload circuit breaker in series connection between one ofsaid contacts and a circuit extension conductor means.

One of the objects of the invention is provision of a simplifiedcombined electric plug in connector and circult breaker which willautomatically protect against overheating the conductors of anelectrical circuit extension from overloading the circuit beyond itspredetermined safe current carrying capacity.

A further object of the invention is the provision of a plugconnector-circuit breaker combination thermally responsive to currentload conditions to open the circuit on current overload and with meansto prevent arcing and reclosing of the circuit until manually reset,and, in modified form, a connector-breaker arrangement of the kindwherein the arc prevention and circuit reclosing prevention means may bealso manually operable to open and close the circuit under normal loadconditions.

Other objects and advantages of the invention will become apparent fromthe following specification and by reference to the drawings forming apart thereof, where- 1n:

FIG. 1 is a view partly broken in elevation showing conductors andconductor-circuit breaker assemblies as positioned and held betweenjoined internally recessed body portions of the plug.

FIG. 2 is a broken cross sectional view on line 2-2 of FIG. 1 in thedirection of the arrows.

FIG. 3 is a detail plan view of circuit breaker arrangemerit as in FIG.2 but with element 12 broken away and with a modified insulator slide.

Having reference tto the drawing, the structural combination comprisesan insulating body of mating half sections 1 and 2, each internallyrecessed to receive, position and anchor therebetween in respectivereceiving recesses therefor a plug contact and conductor assembly 3; aplug contact, thermal circuit-breaker and conductor assembly 4; and adielectric arc preventing operating means 5 and its actuating spring 6.

The contact and conductor assembly 3 includes a blade contact 7 with aportion thereof within the plug body shaped in conformity to a receivingrecess in the body so that opposing shoulders and side walls of the bodydefining the recess position the contact and prevent side or endwisemovement thereof, a conductor portion 8, which may be as shown integralwith the contact or otherwise and fixed thereto, not shown, pass throughthe plug body terminating in connection with a circuit extensionconductor 10 or its equivalent as at 9, or in any other manner of goodelectrical connection.

The plug contact, thermal-circuit breaker and conductor assembly 4includes a blade contact 11 also shaped, positioned and held in the bodyin manner described for contact 7, and has fixed thereto as by riveting13 a bimetallic thermostatic member 12 which comprises joined strips ofconductive metal or metal alloy having different coefficients ofexpansion. This member 12 has fixed thereto at its free end a contact 14raised from the surface of thermostatic member. A second correspondingbimetallic member 15 carries raised contact 16 at its free end and ispositioned and held at its other end between the body sections in aconforming recess so that the free ends of the bimetallic membersoverlap with the contacts thereon normally held in abutting conductiverelationship. Member 15, at its fixed end is provided as at 17 or thelike for connection with a circuit extension conductor here illustratedas wire 18.

Composite strips of conductive metal or alloys of differing coefficientsof expansion, employed as thermal responsive conductor elements inelectric circuit breaking operations, are not new in the art. So used,however, under substantial current carrying loads there is likelihood ofdrawing a substantial and damaging arc in contact separation mainly fromlack of speed in such separation. Thermal responsive conductor elements12 and 15 are designed, shaped and held in the insulating body of theplug with contacts 14 and 16 in firm conductive engagement to remain sounder normal heating through a predetermined safe current consumptionload range in circuit extensions from the plug. In event of overloadingsuch circuits beyond the predetermined safe current load range for whicha particular circuit breaker is designed, resultant overheating ofelements 12 and 15 causes each bimetallic element and its contact toquickly swing away from each other in opposite directions. This speed ofcontact separation is aided and enhanced by the insulator slide operator5 moving transversely between the contacts and insulating one from theother.

Operator 5 is provided intermediate its end portions with an aperture toprovide passage therethrough of the contacts in making and breakingengagement, and to provide side portions of the slide straddling thecontacts and connecting the end portions. This slide has restrictedtransverse movement in the plug in a guide recess formed between theplug portions. At one end portion the insulator slide has a narrowed endextension defining stop shoulders on the slide adapted to engage innersurfaces of the plug body to limit movement of the slide in onedirection, the narrowed end extension, in the so stopped position of theslide, extending outward of the plug body providing a portion to beengaged by a finger to reset the slide. At its other or opposite endportion the insulator slide is centrally recessed providing side legportions which in movement of the slide have end engagement with innersurfaces of the plug body to limit movement of the insulator slide indirection opposite to that first mentioned. Spring 6 is positioned in arecess in the plug body to bear at one end on inner surface portion ofthe plug body and at the other end against a transverse portion of theslide disposed between the end recess and the slide aperture. Thistransverse portion of the slide in normal use of the device has a pointedge bearing with the raised side edges of the contacts under pressureof spring 6. The force applied to the insulator slide by spring 6produces instantaneous projection of the slide when the contacts open onoverload but is insufficient to cause opening of the contacts which arefeld firmly closed by the much greater power exerted by the compositemembers 12 and 15 under normal heating throughout the predetermined safecurrent load range for which the connector is designed.

When power demands in extension circuits from the connector reachoverload values, abnormal heating of composite conductors 12 and 15results, causing the free contact carrying ends of the members to flexaway from each other, thus breaking the circuit by separation of thecontacts. In this operation the power of the composite conductorsnormally holding the contacts together is relaxed allowing the insulatorslide to be projected where it becomes interposed between the contactspreventing reclosing of the contacts on cooling of composite conductors.In its projection between the contacts, the operation of the slideenhances somewhat the speed of contact separation. The insulator slideremains in the projected position preventing reclosing of the circuituntil it is manually reset by an operator by inward pressure applied tothe narrowed end portion of the slide to compress spring 6 and allowreengagement of the contacts.

In FIG. 3 there is shown in broken plan view a modified slide operatorhaving at the recessed or spring loaded end of the insulator slide afinger operable projection which extends outwardly of the plug structurewhen the slide is in its retracted position. Added power may be appliedby an operator by finger pressure on slide operating extension to movethe slide in wedging action between the contacts, the portion of theinsulator slide in engagement with the contacts and the edge portions ofthe contacts being rounded or beveled to render the separationrelatively easy under application of the added manual power. Soseparated, the contacts remain insulated from each other by theinsulator slide until the slide is reset manually by pressure applied toits opposite end to restore it to its normal operative position.

The connector body portions may be of any suitable insulatingcomposition interiorly and accurately recessed in receiving conformitywith the insulator slide, forming a guide recess therefor, and theconductive assemblies designed and contoured for positioning fittherein. These assemblies are detachably mounted by mere insertion intheir respective recesses, the other body portion is then applied andthe combination is then fixed together by tubular riveting in knownmanner or by the screw bolts 21 as shown.

Having described the invention in connection with a particularembodiment thereof, words employed are those of description rather thanof limitation, and changes within the purview of the appended claim arecontemplated without departure from the true scope and spirit of theinvention.

I claim:

1. An electrical plug connector and overload current circuit breaker forbranch circuit connections therefrom, an insulator body of mating halfportions recessed interiorly and longitudinally in conformity withconductor assemblies to be anchored therein and transversely recessed toreceive and hold a dielectric slide member for limited slidable movementtransversely of the plug, spaced conductor assemblies conforming to theprovided recesses therefore extending longitudinally thereof the bodyanchored therein between the body portions, said spaced conductorassemblies comprising one unit comprising a continuous conductor elementhaving binding terminal means at one end thereof and plug contact meansextending outwardly of the plug body at the other end and a secondconductor assembly of two aligned structural units one having plugcontact means extending outwardly of the plug at one end and connectedtherewith at an inner end a bimetallic strip of metals with differentcoeflicients of expansion having a contact mounted at the free end ofthe strip, the other unit comprising a bimetallic strip of metals withdifferent coefficients of expansion having binding terminal means at oneend and at a free end a contact mounted thereon overlapping said firststrip free end with the contacts in abutting engagement in circuitcontinuity, a finger operable dielectric slide contoured and aperturedat a central portion thereof for passage therethrough of the abuttingcontacts, said slide being mounted in the transverse recess of theinsulator body having limited slide movement in the recess in the planeof abutment of the contacts on free ends of the strips and having aninner edge portion bounding the recess normally in engagement with theclosed contacts, spring means maintaining the slide in such engagementunder normal operating conditions but causing the slide to move ininterposed contact covering position between the contacts to insulatethe same and prevent arcing therebetween in event of overload, saidbimetallic strips tending to close and hold closed the contacts butdesigned to flex in opposite directions to separate the contacts inevent of current passage in excess of that for which the breaker isdesigned, and, reengagement of the contacts being prevented until theslide is manually operated to reset position, said slide being alsooperable from its reset position manually to open the breaker.

References Cited UNITED STATES PATENTS 2,567,361 9/1951 Bean 200116 X2,669,625 2/1954 Roberts et al. 200 2,745,924 5/1956 Coates 2001383,209,104 9/1965 Malone 200138 X 3,300,607 1/1967 Delafrange 200115.5

BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWITTER, R. L. COHRS, Assistant Examiners.

